A variety of conveyor systems have been designed and utilized to move materials from one location to another. By way of example, conveyor systems are used to move sand, gravel, crushed ore or rock, coal, and other materials, depending upon the particular industry involved. A large variety of known conveyor systems comprise a continuous belt or conveyor medium which travels over a series of conveyor rollers.
Typically, such conveyor systems utilized at least one conveyor drive roller which has a roller surface that is caused to rotate by an electric, hydraulic, or pneumatic motor positioned inside or outside of the conveyor drive roller. The conveyor drive roller translates the rotational movement of the roller surface to linear movement of the conveyor medium. In addition to one or more conveyor drive rollers, the conveyor system may include one or more conveyor idler rollers, which are not driven, and merely serve to support the conveyor medium as it moves thereover driven by the one or more conveyor drive rollers in the conveyor system.
By way of example, other prior art conveyor drive rollers are disclosed in U.S. Pat. Nos. RE44,919, RE44,907, 5,934,447, 6,766,900, 6,837,364, 6,938,754, 7,204,359, 7,228,952, 7,244,205, 7,510,073, 7,753,193, 7,806,252, 7,870,949, 8,292,064, and 9,284,131.
Conveyor driver rollers typically have a rotatable supporting surface, which is often covered by some form of surface arrangement to increase the co-efficient of friction between the conveyor drive roller and the conveyor medium, reduce the wear on the conveyor drive roller and the conveyor medium, and in some cases effect a self-cleaning action as particularized in U.S. Pat. No. 5,213,202. A typical surface arrangement is in the form of a continuous layer of rubber, or rubber-like material attached or bonded to the circumference of the rotatable supporting surface. Such a covering is sometimes referred to as lagging. The covering can include a multitude of materials that are attached by various methods. The most commonly used lagging is made of elastomeric components, which are bonded and cured by vulcanization to the conveyor drive roller and extend around the circumference of the rotatable supporting surface of the conveyor drive roller. Other common methods of attaching the lagging materials to the conveyor drive roller include bolting, painting, cementing, or spraying.
Similarly, conveyor idler rollers may also have a rotatable supporting surface, which is covered by some form of surface arrangement to reduce the wear on the conveyor idler roller and the conveyor medium, and in some cases effect a self-cleaning action.
In use, large forces are exerted on the lagging of conveyor rollers, including conveyor drive rollers and conveyor idler rollers, and mixed with the harsh environments in which conveyor rollers operate, over time, the lagging becomes worn or damaged. When that happens, the conveyor system must be stopped so that the conveyor roller may be removed from the system, inspected, and replaced or repaired. A worn lagging may signal a gentle failure requiring a planned shut down of the conveyor system, to permit repair or replacement at a time that is convenient for the operator. However, a damaged lagging may signal a critical failure requiring an unplanned shut down to avoid further damage to the conveyor roller itself, or damage to the other components in the conveyor system, such as for example, the conveyor medium and downstream components.
Conventionally, conveyor rollers have lagging arranged on their rotatable surface as a continuous sleeve of material which is friction fit or bonded to the rotatable supporting surface. However, over time, such a surface arrangement is prone to critical failure, requiring an unplanned emergency shut down, mentioned above. This is because a failure of the bond (i.e. delamination) in one portion along the circumference of the rotatable supporting surface quickly spreads to the remaining portions, resulting in damage to, and/or shedding of the entire lagging. Often this form of failure results in a critical condition in the operation of the conveyor system, which signals an operator to effect an unplanned emergency shut down of the conveyor system. When this happens, the conveyor system remains out of commission until the damaged conveyor roller can be replaced or repaired.
U.S. Pat. No. 3,354,735 (Holz), U.S. Pat. No. 3,789,682 (Holz), U.S. Pat. No. 4,4824,409 (Van Teslaar), U.S. Pat. No. 4,718,544 (Herren), and U.S. Pat. No. 4,832,669 (Holz), disclose attempts at overcoming some of the problems associated with replacing worn or damaged lagging on conveyor rollers. For example, U.S. Pat. No. 3,354,735 (Holz), U.S. Pat. No. 3,789,682 (Holz), U.S. Pat. No. 4,4824,409 (Van Teslaar), U.S. Pat. No. 4,718,544 (Herren), and U.S. Pat. No. 4,832,669 (Holz), each disclose a conveyor surface arrangement comprising a plurality of separate sections attached to the surface of the conveyor roller, wherein each section comprises a rubber material bonded to a metal backing plate. The sections are attached to the conveyor roller surface by their metal backing plates. U.S. Pat. No. 4,284,409 discloses securing the backing plates to the surface of the conveyor roller using fasteners. U.S. Pat. Nos. 4,718,544 and 4,832,669 disclose welding the backing plates to the surface of the conveyor roller. U.S. Pat. Nos. 3,354,735 and 3,789,682 disclose providing strips or tabs on the surface of the conveyor roller to serve as guides or retaining members configured to slidingly receive the metal backing plates, and then securing the metal backing plates to the surface of the conveyor roller with fasteners or by welding.
However, problems exist with the conveyor roller surface arrangements disclosed in the above noted patents. The foremost is the increased cost associated with manufacturing the metal backed lagging sections for attachment to the surface of the conveyor roller. In particular, necessitating the metal backing plate for attachment to the surface of a conveyor roller requires additional materials and labour costs to make the conveyor roller, as compared to a conveyor roller in which lagging is attached directly to the surface of the conveyor roller without using a metal backing plate. The metal plate backed lagging sections also require specialized equipment for their manufacture, which adds further to the cost of their manufacture.
Additionally, the metal plate backed lagging sections impose a further storage related cost. One will appreciate that since the metal plate backed lagging sections are manufactured with specialized equipment to conform to predetermined shapes and sizes, an operator of a conveyor system incorporating conveyor rollers with the pre-made metal plate backed lagging sections, or a conveyor system repair facility will need to stock metal plate backed lagging sections of different dimensions specific to each of the different conveyor rollers. Such a requirement imposes an associated storage costs.
Furthermore, necessitating securing the metal plate backed lagging sections to conveyor rollers by using fasteners or welding, as taught in the above noted patents, increases labour costs associated with replacing worn or damaged sections, since additional labour is required to remove the fasteners and/or the welds used to secure the metal plate backed sections.
Other prior art patents of general interest in the field of conveyor roller surface arrangements include U.S. Pat. No. 6,89,521 (Titus), U.S. Pat. No. 3,789,682 (Holz), U.S. Pat. No. 6,168,544 (Barnes), and U.S. Pat. No. 6,692,392 (Finnegan), and U.S. Pat. No. 4,821,871 (Herren).
Therefore there is a continuing need for improvement in the design of conveyor roller surface arrangements.